Phytophthora dieback1.02 MB - Department of Parks and Wildlife

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A guide to managing and restoring
wetlands in Western Australia
Phytophthora dieback
In Chapter 3: Managing wetlands
OV
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Our environment, our future
A guide to managing and restoring wetlands in Western Australia
Introduction to the guide
Western Australia’s unique and diverse wetlands are rich in ecological and cultural values
and form an integral part of the natural environment of the state. A guide to managing
and restoring wetlands in Western Australia (the guide) provides information about the
nature of WA’s wetlands, and practical guidance on how to manage and restore them for
nature conservation.
The focus of the guide is natural ‘standing’ wetlands that retain conservation value.
Wetlands not addressed in this guide include waterways, estuaries, tidal and artificial
wetlands.
The guide consists of multiple topics within five chapters. These topics are available in
PDF format free of charge from the Western Australian Department of Environment and
Conservation (DEC) website at www.dec.wa.gov.au/wetlandsguide.
The guide is a DEC initiative. Topics of the guide have predominantly been prepared by
the department’s Wetlands Section with input from reviewers and contributors from a
wide range of fields and sectors. Through the guide and other initiatives, DEC seeks to
assist individuals, groups and organisations to manage the state’s wetlands for nature
conservation.
The development of the guide has received funding from the Australian Government, the
Government of Western Australia, DEC and the Department of Planning. It has received
the support of the Western Australian Wetlands Coordinating Committee, the state’s
peak wetland conservation policy coordinating body.
For more information about the guide, including scope, purpose and target audience,
please refer to the topic ‘Introduction to the guide’.
DEC welcomes your feedback and suggestions on the guide. A publication feedback
form is available from the DEC website at www.dec.wa.gov.au/wetlandsguide.
ii Phytophthora dieback
Chapter 3: Managing wetlands
Contents of the guide
Introduction
Introduction to the guide
Chapter 1: Planning for wetland management
Wetland management planning
Funding, training and resources
Chapter 2: Understanding wetlands
Wetland hydrology
Conditions in wetland waters
Wetland ecology
Wetland vegetation and flora
Managing hydrology
Wetland weeds
Water quality
Secondary salinity
Managing wetland vegetation
Nuisance midges and mosquitoes
Introduced and nuisance animals
Livestock
Chapter 4: Monitoring wetlands
Monitoring wetlands
Chapter 5: Protecting wetlands
Roles and responsibilities
Legislation and policy
These topics are available in PDF format free of charge from the DEC website at
www.dec.wa.gov.au/wetlandsguide.
iii Phytophthora dieback
‘Phytophthora dieback’ topic
Acknowledgments
Author: Christina Mykytiuk, DEC
Editor: Justine Lawn, DEC
Reviewers and contributors
The following people have been consulted in the development of this topic:
Chris Dunne, DEC
Michael Pez, DEC
Anthony Raudino, DEC
Ben Deeley, City of Bunbury
Val English, DEC
Andrew Webb, DEC
Dr Bryan Shearer, DEC
Dr Lien Sim, DEC
Justine Lawn, DEC
Dr Ken Atkins, DEC
The valuable contribution of each of these people, and people who have contributed
their photos, is gratefully acknowledged.
Project manager: Justine Lawn, DEC
Publication management: Paul Rochford, Joanna Moore, DEC
Graphic design: Maria Duthie, Gooitzen van der Meer, Sonja Schott, DEC
Cover photo: Manning Lake, Cockburn, courtesy of Prof. Jenny Davis.
Recommended reference
When referring to the guide in its entirety, the recommended reference is: Department
of Environment and Conservation (2012). A guide to managing and restoring wetlands
in Western Australia. Department of Environment and Conservation, Perth, Western
Australia.
When specific reference is made to this topic, the recommended reference is:
Department of Environment and Conservation (2012). ‘Phytophthora dieback’, in A
guide to managing and restoring wetlands in Western Australia, Prepared by C Mykytiuk,
Department of Environment and Conservation, Western Australia.
Disclaimer
While every effort has been made to ensure that the information contained in this
publication is correct at the time of printing, the information is only provided as a guide
to management and restoration activities. DEC does not guarantee, and accepts no
legal liability whatsoever arising from or connected to, the accuracy, reliability, currency
or completeness of any material contained in this guide. This topic was completed in
June 2009 therefore new information on this subject between the completion date and
publication date has not been captured in this topic.
iv Phytophthora dieback
Contents
Introduction 1
What is Phytophthora dieback? 3
What causes the spread of Phytophthora dieback in Western Australian wetlands? 5
What effect does Phytophthora dieback have on wetlands? 6
Effects on vegetation 6
Effects on native animals 10
What types of Western Australian wetlands are commonly affected by
Phytophthora dieback? 10
Extent of infestation 12
Recognising the symptoms of Phytophthora dieback 12
Indicator species 12
Interpreters 13
Aerial photography 14
Ground stripping 14
Sampling to determine the presence of Phytophthora cinnamomi 15
Mapping Phytophthora dieback 16
Key management techniques for tackling Phytophthora dieback in wetlands 17
Assessing a wetland for Phytophthora dieback 17
Preparing and implementing management procedures 17
Treating plants with phosphite 19
Monitoring the success of management and restoration techniques 21
Whether or not to manage Phytophthora dieback in a wetland 23
Topic summary 24
Sources of more information on managing Phytophthora dieback in wetlands 25
Glossary 26
Personal communications 26
References 27
Case studies
Critically endangered wetlands threatened by Phytophthora dieback Manea Park – a collaborative approach to Phytophthora dieback management v Phytophthora dieback
8
22
h
Phytophthora dieback: the
introduced plant disease caused
by Phytophthora cinnamomi,
which results in the decline or
death of susceptible plants
Before you begin
Before embarking on management and restoration investigations and
activities, you must consider and address the legal requirements, safety
considerations, cultural issues and the complexity of the ecological
processes which occur in wetlands to ensure that any proposed actions
are legal, safe and appropriate. For more guidance, see the topic
‘Introduction to the guide’.
Introduction
Phytophthora dieback refers to the introduced plant disease caused by Phytophthora
cinnamomi (pronounced fy-tof-thora – meaning plant destroyer in Greek). The impacts
of Phytophthora dieback were first detected in Western Australian forests in the 1920s.
The pathogen itself, a water mould, P. cinnamomi, was identified in the mid 1960s and
since then management procedures have been introduced to combat the disease and
minimise its spread.
The arrival and spread of P. cinnamomi in WA has been catastrophic for the plants and
animals of many south-western ecosystems, including wetlands (Figure 1). As many as
2,300 of the estimated 5,700 native plant species in the south-west are susceptible to,
and often killed, by the pathogen. Phytophthora dieback has been recognised as a key
threatening process under the Commonwealth Environment Protection and Biodiversity
Conservation Act 1999. It is now considered to be a bigger threat to Western Australia’s
natural ecosystems than salinity and is estimated to cost the Australian economy $160
million each year.1 In addition, P. cinnamomi has caused major problems for road
construction, timber harvesting, mining and other industries since researchers realised
that the movement of soil is the most likely method of spread of the pathogen.
There are several other species of Phytophthora present in native vegetation in the southwest of WA, including P. cryptogea, P. multivora and P. nicotianae, but their extent and
impact on native vegetation is unclear.
1 Phytophthora dieback
Phytophthora cinnamomi: an
introduced water mould that
attacks the roots of susceptible
plant species, resulting in the
decline or death of the plant
Pathogen: any organism or
factor causing disease within
a host
Dieback: the progressive
dying-back of a plant as a result
of disease or unfavourable
conditions
Figure 1. The effects of Phytophthora dieback in a seasonally waterlogged wetland near
Busselton in the south-west of WA. Photo – C Mykytiuk/DEC.
Historically, Phytophthora dieback has also been known as ‘dieback’ and ‘jarrah dieback’.
The use of these names has contributed to the confusion about the disease. For example,
the term ‘dieback’ is used in other parts of Australia to refer to tree decline caused by
factors such as salinity, drought and insect damage. Furthermore, P. cinnamomi affects
a large number of native and introduced plant species in addition to jarrah (Eucalyptus
marginata). To overcome this confusion the term ‘Phytophthora dieback’ is now used.2
What is Phytophthora dieback?
As previously mentioned, Phytophthora dieback refers to the plant disease caused by the
introduced pathogen P. cinnamomi. Phytophthora cinnamomi is a microscopic soil-borne
organism belonging to the Oomycetes or ‘water moulds’. As the name suggests, the
organism depends on moist conditions that favours its survival, reproduction and dispersal.
Phytophthora cinnamomi lives in both soil and plant tissue. It invades the roots of plants
from the surrounding soil to obtain nutrients and moisture for growth and reproduction.
It grows as microscopic-sized filaments, mycelium, on the surface of plant roots.3
The pathogen extends these microscopic filaments into the major roots of susceptible
species causing cell breakdown and the formation of lesions (areas that appear dead or
rotten – see Figure 2). This reduces the ability of a plant to take up and transport water
and nutrients and usually results in plant death.3 In very susceptible species, such as
banksias, death may occur within weeks, while in moderately susceptible species such as
jarrah (Eucalyptus marginata), the tree may not die until a year or more after infection.
Moderately susceptible and resistant species such as flooded gum (E. rudis) have the ability
to ‘wall off’ the infection to prevent further spread of the mycelia, with varying degrees
of success.4
Phytophthora cinnamomi mycelia need environmental conditions to be favourable to
grow within a plant root. For instance, there is little growth when the water content of
the plant tissue is below 80 per cent. The pathogen is able to survive within dead plant
roots and dry soils, by producing tough long-lived spores known as chlamydospores.
These allow the pathogen to persist more easily during the dry summer months of southwest WA.
Figure 2. A Phytophthora cinnamomi lesion in a sheoak (Allocasuarina) trunk with
the bark removed. Photo – Dieback Working Group.
Oomycetes: the group of
fungae-like organisms known
as the water moulds
Mycelium: the vegetative
part of a fungus, consisting of
microscopic threadlike filaments
known as hyphae
extra information
Phytophthora cinnamomi life cycle
Phytophthora cinnamomi feeds
on living plant roots and stems.
It invades the roots of plants to
get the nutrients it needs. This
invasion and growth within the
plant reduces the plant’s ability
to transport water and nutrients,
often resulting in death of the
host plant.
Phytophthora cinnamomi is
able to reproduce through
the production of microscopic
fruiting bodies which release
spores. Four types of spores are
produced—sporangia, zoospores,
chlamydospores and oospores
(Figure 3 and described below).
Sporangia
Sporangia are the largest of all the
spores and are produced under
favourable temperature and soil
moisture conditions. Zoospores are
produced internally in sporangia
and are released into soil once the
sporangia reach maturity.
Figure 3. Life cycle of Phytophthora cinnamomi. © Dieback Working Group.5
Zoospores
Zoospores are short-lived and fragile, but are produced
in large numbers under moist soil conditions and
are probably the cause of most new infections.
Produced by sporangia, zoospores have flagella
(tails), which allow them to swim very short distances
(25–35 millimetres) in standing water or in films of
water in soil pores. They can also be carried along
in moving water over large distances. As they move
through the soil, zoospores are attracted to the tips of
plant roots, where they lodge, and then germinate
(begin to grow, usually after a period of dormancy)
to produce germ tubes which penetrate roots. Once
inside the plant, the germ tube develops into mycelia
which grow within the roots of susceptible plants, and
may grow from plant-to-plant via root contact points.
This root-to-root growth is the main cause of spread of
a Phytophthora infestation in an upslope direction.
Chlamydospores
These are much larger than zoospores and are tough
and long-lived (within dead plants and the soil). They
are produced within plant roots in response to drying
conditions, and are the ‘resting’ phase of the water
mould. Chlamydospores are resistant to drying-out
and are one of the mechanisms the pathogen has
developed to help it survive adverse conditions.
They may be transported in root fragments or soil
and then germinate to cause a new infection when
they encounter warm, moist conditions. Germinated
chlamydospores may produce sporangia, more
chlamydospores, or mycelia which directly infect roots.
Oospores
Oospores are produced through the sexual
recombination of two different forms of the pathogen
(A1 and A2 mating types). The sexually produced
oospores are round and thick-walled, and are
considered highly resistant to degradation. In some
Phytophthora species, oospores are an important
mechanism of surviving harsh environmental
conditions. Although both mating types do occur
together in some infested sites in WA, there is limited
evidence of sexual recombination, and thus oospore
production, occurring in the natural environment in
this state.
What causes the spread of Phytophthora dieback in
Western Australian wetlands?
Phytophthora cinnamomi is transported by two main mechanisms. The first is the
movement of its spores through free water (including groundwater in coarse-textured
soils and water-filled root channels), or by root-to-root contact between plants.6 The
second is through the movement of infected soil or plant material around the landscape.
It is the movement of infected soil and plant material that has caused the large-scale
spread and devastating impacts of Phytophthora dieback in the south-west of WA.
Phytophthora dieback is able to spread quickly down slopes and cover long distances if
infected water is able to move freely. Its movement is much slower up slope and on flat
ground (around one metre per year) as movement is generally restricted to root-to-root
contact. Any action or process, including water movement, which transports soil in the
landscape can also potentially transport the pathogen to a new site. Wetlands that are
located in the lowest points in the landscape, and receive water from throughout the
catchment, are at a high risk of being infested by Phytophthora cinnamomi.
The main cause of the spread of infected soil and plant material is transport by humans
and some animals. Phytophthora cinnamomi can be carried by animals such as horses
and wild pigs, often in soil attached to hooves and fur. It is transported by: humans
on boots, in the muddy tyres of vehicles travelling along infested tracks, in plant pots,
through earth moving and some vegetation clearing activities, and road construction.2
Warm, moist soil provides ideal conditions for the spread of P. cinnamomi. These
conditions enable the pathogen to produce millions of zoospores. The zoospores are
then attracted to plant roots as they seek out moisture and nutrients, swimming through
soil water.2
h
High risk activities for transporting
Phytophthora cinnamomi
Activities with a high risk of transporting Phytophthora cinnamomi
include:
•
removal of groundwater and surface water from wetlands potentially
contaminated with P. cinnamomi for activities such as dewatering,
irrigation and fire fighting
•
transport of soil to and from wetlands potentially containing the
pathogen
•
fire break construction, which can result in the movement of soil
around a property and between properties1
•
revegetation activities that may potentially introduce P. cinnamomi
to an area if the potting mix or soils used are contaminated with the
pathogen
•
movement of equipment and vehicles for a range of purposes,
including the construction and maintenance of linear corridors such
as roads, railways, gas pipelines and powerlines.
What effect does Phytophthora dieback have on
wetlands?
Effects on vegetation
Over 40 per cent of the native plants in south-west WA are susceptible to Phytophthora
dieback.7 In field studies of south-western plant communities the families with the
highest proportion of susceptible species were: Proteaceae – banksia family (92 per cent);
Epacridaceae – heath family (80 per cent); Papilionaceae – pea family (57 per cent); and
Myrtaceae – myrtle family (16 per cent) (Table 1).
Very little research has been undertaken on the effects of Phytophthora dieback on
wetlands. Many common wetland plant species in the south-west such as flooded gum
(Eucalyptus rudis), moonah (Melaleuca preissiana) and white myrtle (Hypocalymma
angustifolium) are resistant to Phytophthora dieback (see Figure 4). Yet common species
such as swamp peppermint (Taxandria linearifolia), swamp banksia (Banksia littoralis) and
swamp teatree (Pericalymma ellipticum) have been identified as being susceptible (see
Figure 5). Field observations have suggested that many wetland species are resistant to
the disease (C Dunne 2008, pers. comm.), hence wetland plant communities often don’t
exhibit signs of Phytophthora dieback. Although many wetland species may be resistant
to Phytophthora dieback, they may still act as resistant hosts for the pathogen (C Dunne
2008, pers. comm.).
Table 1. Examples of wetland species susceptible to Phytophthora dieback
in the south-west by plant family
Family
Species – scientific name
Species – common name
Adenanthos obovatus
Basket flower
Banksia littoralis
Swamp banksia
Epacridaceae
Sphenotoma gracilis
Swamp paper-heath
Papilionaceae
Jacksonia horrida
-
Melaleuca thymoides
-
Verticordia densiflora
Compacted featherflower
Proteaceae
Myrtaceae
Garden species susceptible
to Phytophthora dieback
A number of garden and
horticultural plants are
susceptible to Phytophthora
cinnamomi including:
• apple, peach, apricot and
avocado trees
• roses
• camellias
• azaleas
• proteas
• rhododendrons8,9
Figure 4. (below) Common south-west wetland species resistant to Phytophthora dieback.
Photos – (a) ND Burrows and SD Hopper; (b) C Horton; (c) M Seale and J Stevens. Images used
with the permission of the Western Australian Herbarium, Department of Environment and
Conservation http://florabase.dec.wa.gov.au/help/copyright, accessed 4/2/2009.
(a) Flooded gum (Eucalyptus rudis) (b) Moonah (Melaleuca preissiana)
(c) White myrtle (Hypocalymma angustifolium)
Figure 5. (below) Common south-west wetland species susceptible to Phytophthora dieback.
Photos – (a) BA Fuhrer, M Hancock, A Ireland and E Wajon; (b) I and M Greeve, C Hortin
and T Tapper; (c) A Ireland and M Hislop. Images used with the permission of the Western
Australian Herbarium, Department of Environment and Conservation http://florabase.dec.
wa.gov.au/help/copyright, accessed 4/2/2009.
(a) Swamp peppermint (Taxandria linearifolia) (b) Swamp banksia (Banksia littoralis)
(c) Swamp teatree (Pericalymma ellipticum)
case study
Chapter 3: Managing Wetlands
Critically endangered wetlands threatened by
The following information has been taken from
the then Department of Conservation and Land
Management (CALM) (2005).10
The ‘Shrublands on southern Swan Coastal Plain
ironstones’ (Busselton ironstone community)
is a species-rich plant community of seasonally
inundated wetlands with ironstone and
heavy clay soils on the Swan Coastal Plain
near Busselton (Figure 6). The community is
recognised as being critically endangered on
the list of threatened ecological communities
endorsed by the Western Australian Minister for
Environment. In 1995 there were only thirteen
known occurrences of the Busselton ironstone
community totalling 90 hectares. As a result of
further surveys, the area of these occurrences has
been found to be bigger than first thought and
two additional occurrences have been identified
bringing the total area of the community to
almost 140 hectares.
The ironstone soils on which the Busselton
ironstone community occurs are extremely
restricted in distribution on the Swan Coastal
Plain. They occur only on the eastern side of the
Swan Coastal Plain along the base of the Whicher
Scarp near Busselton. The heavy soils of this area
are particularly useful for agricultural purposes.
It has been estimated that around 97 per cent
of vegetation on the eastern side of the Swan
Coastal Plain has been cleared.
Figure 6. Busselton ironstone community.
Photo – C Mykytiuk/DEC.
Much of the species diversity of the Busselton
ironstone community is made up of annuals and
geophytes (land plants that survive unfavourable
periods by means of underground food storage
organs, for example, rhizomes, tubers and
bulbs). Typical and common native species are
the shrubs Kunzea aff. micrantha, Pericalymma
ellipticum, Hakea oldfieldii, Hemiandra pungens
and Viminaria juncea, and the herbs Aphelia
cyperoides and Centrolepis aristata. The
community contains a number of taxa that are
listed as priority or declared rare flora (DRF) by
the Western Australian Government and are
either totally confined or largely confined to these
areas.10
Major threats to the community include
Phytophthora dieback, clearing, too frequent
fires, weed invasion, hydrological changes, and
possibly salinisation. A number of plant species
that occur in the community are very susceptible
to Phytophthora dieback, including Banksia
nivea subsp. uliginosa (Figure 7). All but one of
the fifteen occurrences of the plant community
are thought to be infected with the disease.10
As such, Phytophthora dieback has the potential
to seriously impact the ‘Shrublands on southern
Swan Coastal Plain ironstones’.
Figure 7. Death of Banksia nivea subsp. uliginosa
(in the foreground) from Phytophthora dieback in an
occurrence of the Busselton ironstone community.
Photo – A Webb/DEC.
When P. cinnamomi invades communities dominated by species from the Proteaceae
family, such as banksias and grevilleas, substantial changes in plant abundance and
floristic structure may be observed. However, the effect of Phytophthora dieback on
a plant community can vary greatly, depending both on the species composition of
a particular community, and on the prevailing environmental conditions. It has been
found that within the portion of the south-west land division that receives more than
800 millimetres mean annual rainfall, plant communities respond to Phytophthora
dieback in one of four distinct ways:
1. No apparent disease at all (Figure 8).
2. An extremely destructive epidemic of root rot.
3. A variable epidemic within the dominant tree component of the jarrah forest,
characterised by:
a. irregular and often prolonged death of trees ranging from early localised mass collapse, through delayed and patchy deaths, to no apparent effect on the health of the jarrah overstorey
b. high sensitivity to subtle differences in soil characteristics particularly those affecting drainage.
4. Replacement of forest with open woodland.11
The loss of native vegetation as a result of Phytophthora dieback (both within and
surrounding a wetland) can have a number of detrimental impacts including:
• increased erosion and sedimentation
• reduced water quality
• loss of biodiversity, both directly and through loss of habitat and food for native
fauna.
➤ For additional detail on the impacts of vegetation loss, see the topic ‘Managing
wetland vegetation’ in Chapter 3.
Figure 8. Wetland vegetation infested with Phytophthora cinnamomi but showing no signs of
the disease. Photo – R Lynch/DEC.
Effects on native animals
Changes in plant community composition and structure caused by P. cinnamomi may
adversely affect associated groups of animals and soil biota by altering the availability of
food resources and habitat (Table 2). Large herbivores such as western grey kangaroo
(Macropus fuliginosus) and western brush wallaby (M. irma) may become more common,
while smaller animals such as bandicoots and frogs may suffer from loss of refuge, with the
more open vegetation giving them less protection from predators.
Pollinators reliant on susceptible plant species as key nectar sources, such as western
pygmy-possum (Cercartetus concinnus) and honey possum (Tarsipes rostratus) may
become rare or extinct in areas which have lost many species as a result of being infested
for a long time. Insect pollinators may also be adversely affected by a reduction in nectarproducing plants, which in turn may affect the reproductive success of surviving plants
dependant on the pollinators.
Table 2. Potential effects on fauna due to vegetation loss from Phytophthora dieback (based on
Wilson, 199412)
Effects on vegetation
Effects on fauna
Loss of susceptible plants in the
understorey and midstorey
Direct loss of food sources such as seeds, nectar and pollen
Decline in plant species richness and
diversity
Decrease in plant cover, increase in
bare ground, erosion
Decrease in canopy cover
Decrease in litter fall
Post-infection increase in frequency of
resistant species
Indirect loss of food sources such as invertebrates
Loss of food for species that prefer floristically rich
vegetation
Loss of seasonal food
Loss of habitat for species dependant on thick ground cover
Increased predation risk
Changes to microclimate
Loss of food for tree-dwelling species
Decline in litter invertebrates
Decline in invertebrate food sources for insectivores
Changes in food webs
What types of Western Australian wetlands are
commonly affected by Phytophthora dieback?
Phytophthora dieback is now widespread throughout the south-west of WA (Figure
9). In general, Phytophthora cinnamomi is restricted to areas in the south-west of the
state receiving at least 400 millimetres of average annual rainfall; between Eneabba in
the north and Cape Arid near Esperance in the east. It may, however, exist in slightly
drier regions in water retaining sites such as wetlands and waterways. The pathogen
causes the greatest impact in areas that receive more than 600 millimetres of annual
rainfall. Phytophthora cinnamomi does not establish on coastal limestone soils of high pH
(although other species of Phytophthora may) suggesting that wetlands on this substrate
are unlikely to be infected.13
The degree to which plant communities are infested by P. cinnamomi is dependant on
several factors, including the length of time the disease has been present, the history
of land use, species susceptibility and landscape and soil factors. The location of many
wetlands low in the landscape means that they have a high likelihood of being infested
if P. cinnamomi is located within their catchments, particularly if infested waterways or
other drainage lines direct surface water into them. If food and oxygen are available, and
temperature, chemistry and microflora are not inhibitory, P. cinnamomi is also able to
survive in groundwater.14 Other than the jarrah forest, little is known of the movement
of P. cinnamomi in groundwater. Although P. cinnamomi can be transported via
groundwater for more than a couple of metres in the jarrah forest, the same movement
may not occur elsewhere and the spread of the pathogen from one infested wetland to
another wetland via groundwater may not occur (B Shearer 2009, pers. comm.). There
are three basic requirements for the rapid, long-distance, lateral (sideways) dispersal of
P. cinnamomi through groundwater:
1. the soil structure must be porous enough (full of holes)
to allow spores to move through15
2. groundwater flow must largely be lateral (sideways)16
3. the connections between larger groundwater pores
must be unbroken over significant distances.17
Figure 9. Distribution of Phytophthora dieback in the south-west of WA.
© Dieback Working Group.
Extent of infestation
According to conservative estimates, 15–20 per cent of the jarrah (Eucalyptus
marginata) forest has been infested by P. cinnamomi, with the proportion considerably
higher in the wetter, north-western part of the forest.13 Around 60 per cent of the
montane shrublands and banksia and mallee woodlands of the 116,000-hectare
Stirling Range National Park are infested, as are perhaps 70 per cent of the seasonally
inundated banksia woodlands in the Shannon and D’Entrecasteaux national parks.13
In contrast, largely because of restricted vehicular access, less than 0.1 per cent of the
328,000-hectare Fitzgerald River National Park is infested with P. cinnamomi, even
though a large part of it receives more than 400 millimetres annual average rainfall.13
There are a number of wetlands in the south-west that have been identified as being
impacted by Phytophthora dieback. These include: Lake Logue near Eneabba; Lake
Warden in Esperance; numerous wetlands on the southern Swan Coastal Plain ironstone
(Busselton area); and wetlands within Jandakot Regional Park and Lightning Swamp
bushland in the Perth metropolitan area.
Recognising the symptoms of Phytophthora dieback
The first step in the management of Phytophthora dieback is determining whether it is
present or absent, and if it is present, identifying which parts of a site are infested.
Indicator species
The first indication that P. cinnamomi has spread into a new area is the death of
‘indicator species’ (Figure 10). An indicator species is a plant species which is reliably
susceptible to P. cinnamomi (i.e. the disease usually kills that species). Common indicator
species in wetlands include the swamp peppermint (Taxandria linearifolia), swamp
banksia (Banksia littoralis), and swamp teatree (Pericalymma ellipticum). The distribution
and composition of indicator species will vary from place to place according to vegetation
type.
➤ Lists of Western Australian native species both susceptible and resistant to
Phytophthora dieback are available on the Centre for Phytophthora Science and
Management website. This list includes both dryland and wetland species.
www.cpsm.murdoch.edu.au18
Figure 10. Deaths of oak-leaved banksia (Banksia quercifolia) in a seasonally waterlogged
wetland within D’Entrecasteaux National Park on the south coast of WA.
Photo – Dieback Working Group.
h
Other causes of plant decline or death
Plant decline and death may be caused by factors other than
Phytophthora dieback. When assessing a site for the presence of
Phytophthora dieback using indicator species, it is important to be able to
discount other causes of plant death or decline such as:
•
insect attack
•
changes to surface water or groundwater levels
•
poor soil or water quality (including nutrient enrichment, acid sulfate
soils and secondary salinity)
•
the honey fungus Armillaria luteobubalina
•
fire
•
nutrient deficiencies.
If Phytophthora dieback ‘resistant species’ such as flooded gum
(Eucalyptus rudis), moonah (Melaleuca preissiana) and white myrtle
(Hypocalymma angustifolium) are dying, then it is likely that the cause is
something other than P. cinnamomi.
When affected by Phytophthora dieback, moderately susceptible plant species such
as jarrah (Eucalyptus marginata) may show symptoms of crown decline including the
yellowing of leaves and death of primary leaf-bearing branches.19 Epicormic buds may
shoot, forming new branches along existing branches, with the leaves on these tending
to be smaller than on the primary branches. Over time, epicormic branches will decline,
resulting in an overall thinning of the crown.19 Trees showing symptoms of crown decline
may take a number of years to die. In some cases, apparently healthy trees (in groups or
individually) can suddenly collapse and die.
Interpreters
The personnel who carry out the tasks of detection, diagnosis and mapping of
Phytophthora dieback are known as ‘interpreters’ because they interpret disease
symptoms to draw conclusions about the health of the vegetation. By recognising
disease symptoms and observing the pattern of indicator species deaths, interpreters can
build up a picture of the history and future progress of the disease at a particular site. As
the pathogen spreads through an area, some or all susceptible plants become infected
and die. Consequently, there will be a spread of ages in the plants that have succumbed
to Phytophthora dieback, ranging from more recent deaths with yellowing or brown
leaves, through to older leafless stags, and finally to remnant stumps in the ground.
Apart from a knowledge of common indicator species, interpreters need to be able to
assess the influence of landscape position, soils and drainage on the development of the
disease and to be able to distinguish the effects of Phytophthora dieback from those of
drought and other diseases of native vegetation such as Armillaria.
Epicormic: (of a shoot or branch)
growing from a previously dormant
bud on the trunk or limb of a tree
Aerial photography
Since 1986, 230-millimetre (1:4,500) colour aerial photographs have been used for
mapping the position of P. cinnamomi disease boundaries in WA. Given sufficient disease
expression (dead and dying plants) at the time of photography, an interpreter can make
decisions about the disease status of an area (that is, whether P. cinnamomi has caused
the deaths). Field visits to view the symptoms and sampling of recently dead plants are used
to verify the interpretation of aerial photographs.
Ground stripping
Ground stripping involves interpreters walking an array of parallel lines through the
bush to determine whether disease caused by P. cinnamomi is present and to record its
position. It is used in areas which are not suitable for interpretation using 230-millimetre
aerial photography or when such photography is not available. Field maps and GPS units
are used to record the position of infected plants and the boundaries of infested areas.
Boundaries are demarcated with painted yellow tree blazes or ‘dayglo’ orange flagging
tape (Figure 11).
Figure 11. Sample being taken from a dead tree for laboratory testing to determine the
presence of Phytophthora cinnamomi. Photo – M Pez/DEC.
GPS: global positioning
system, an accurate worldwide
navigational and surveying
facility based on the reception
of signals from an array of
orbiting satellites
Sampling to determine the presence of Phytophthora cinnamomi
To confirm the accuracy of the interpretation of disease symptoms, samples of root
and lower stem material as well as adjacent soil can be taken from recently dead plants
(Figure 12). Long-dead plants are unlikely to return positive results from sampling even
if P. cinnamomi killed the plant. Collected material can then be sent to an analytical
laboratory for testing. Laboratories offering this service can provide detailed instructions
on how to take a sample, store and transport the collected materials to them.
Laboratories are able to determine the presence of P. cinnamomi using either the
baiting or direct plating method. ‘Baiting’ involves mixing soil from the sample bag with
distilled water in a container and then floating cotyledons (imillimetresature leaves) of
Eucalyptus sieberi (which have purple undersides) on the water. If after five to ten days
the cotyledons have lost their purple colour the sample is presumed to be infected with
P. cinnamomi. ’Plating’ is then carried out by placing the cotyledons on antibiotic agar
in a petri dish. Plated baits are left for a maximum of three days and if P. cinnamomi
is not evident after this time, the plates are discarded, and the samples are recorded as
negative.
It is important to note that a negative result from a sample does not mean that the site is
free of pathogen. A negative result only means that the pathogen was not captured in the
sample. Multiple samples of a site may be required before a positive result can be obtained.
Figure 12. A DEC interpreter marking
the boundary of an area infested with
Phytophthora cinnamomi with yellow tree
blazes and orange flagging tape.
Photo – Dieback Working Group.
Agar: a gelatinous substance
obtained from any of various
kinds of red seaweed and used
to grow cultures of fungi and
other microorganisms
Petri dish: a shallow covered
dish used for the culture of
fungi and other microorganisms
Mapping Phytophthora dieback
Interpreters generally produce two main types of maps, a P. cinnamomi occurrence
map and a P. cinnamomi protectable areas map, both of which are accompanied by
a written report. The P. cinnamomi occurrence map shows disease distribution, and is
used as a basis for the P. cinnamomi protectable areas map and a P. cinnamomi hygiene
management map. Three categories are shown on a P. cinnamomi occurrence map:
uninfested, uninterpretable and infested (Table 3).
A P. cinnamomi protectable areas map shows areas which are disease free, and which are
considered to be able to be protected from the establishment of new centres of infestation
(arising from the activities of humans) through the implementation of hygienic management
practices (Figure 13). The P. cinnamomi hygiene management map is jointly prepared with
the land manager as part of the protectable areas P. cinnamomi hygiene planning process,
and forms part of the P. cinnamomi hygiene plan. The frequency at which these maps
need to be produced will be influenced by the circumstances at a particular wetland.
Table 3. Phytophthora cinnamomi occurrence categories used in maps
Unmappable
Areas that are sufficiently disturbed so that
Phytophthora cinnamomi occurrence mapping is
not possible at the time of inspection
Mappable
Natural undisturbed vegetation. Phytophthora
cinnamomi occurrence mapping is possible
Further categorisation may be possible after variable regeneration periods for different types of
disturbance
Infested
Area that a qualified person had determined to have plant disease
symptoms consistent with the presence of Phytophthora cinnamomi
Uninfested
Area that a qualified person had determined to be free of plant disease
symptoms that indicate the presence of Phytophthora cinnamomi
Area where indicator species are absent or too few to determine the
Uninterpretable presence or absence of Phytophthora cinnamomi
Figure 13. A protectable areas map produced for Manea Park in Bunbury. Map produced by Glevan Consulting for the City of Bunbury.
Key management techniques for tackling
Phytophthora dieback in wetlands
The management of Phytophthora dieback in wetlands can be summarised into three steps:
1. Assess the site and map Phytophthora dieback occurrence
2. Prepare and implement management procedures
3. Treat plants with phosphite.
Assessing a wetland for Phytophthora dieback
As described above, there are a number of ways of assessing a wetland for the presence
of Phytophthora dieback, which include field assessment, analysis of aerial photography
and laboratory testing of plant and soil samples. A key component of an assessment
is determining the distribution of Phytophthora dieback at a site and recording this
information in a P. cinnamomi occurrence map.
As a number of common wetland species are resistant to Phytophthora dieback and may not
show symptoms of the disease, many wetlands may be considered to be ‘uninterpretable’
with regard to detecting the presence of P. cinnamomi. It may therefore be necessary to test
plant and soil samples in a laboratory to confirm the presence or absence of P. cinnamomi
at wetland sites. If a wetland is located low in the landscape and Phytophthora dieback has
already been positively identified within the catchment, it can be assumed with reasonable
confidence it already is or soon will be infested. In such cases it may be considered
unnecessary to have wetland plant and soils samples tested in the laboratory.
More information on assessing a wetland for the presence of Phytophthora dieback is
available in the sections: ‘Recognising the symptoms of Phytophthora dieback’ and ‘Sources
of more information on managing Phytophthora dieback in wetlands’ within this topic.
Preparing and implementing management procedures
Once present, P. cinnamomi cannot be eradicated from an area. As such, the
management of Phytophthora dieback is focused on minimising the spread of the
pathogen. How Phytophthora dieback is managed at a wetland depends largely on
knowing if it is present and having an understanding of its distribution. Whether
Phytophthora dieback is present at the site or not, or is spread throughout an entire site
or located in an isolated section, all management procedures are based on minimising
the movement of soil, plant material and water (hygiene management), and on
protecting plants by treating them with phosphite.
➤ Excellent examples of how to manage Phytophthora dieback in different scenarios
are provided in: Dieback Working Group (2008). Managing Phytophthora dieback in
bushland: A guide for landholders and community conservation groups.2
The basic steps in preparing and implementing Phytophthora dieback management
procedures include:
• Identifying areas which are free of Phytophthora dieback and have a high likelihood
of being maintained as such (‘protectable areas’) and focusing hygiene management
on them
• Implementing hygiene protocols to minimise the spread of Phytophthora dieback
including signage, boot-cleaning stations, vehicle and equipment washdowns (see
Figure 14)
• Setting a timeframe for re-assessing areas for the presence of Phytophthora dieback
and preparing up-to-date occurrence maps
• Utilising up-to-date occurrence maps to review the effectiveness of management
procedures.
Phosphite: an aqueous
solution of mono- and dipotassium phosphite used
to protect plants against
A number of guidelines for the best practice management of Phytophthora dieback have
been produced for a variety of land managers including landholders and community
groups, local government and state government agencies. A list of the best practice
guidelines that have been produced for each of these groups is included in this section.
Please note that the documents listed may be of use to land managers beyond the
targeted group.
It is also worth noting that the guidelines listed below have been written with dryland
bushland rather than wetlands in mind. When relating management guidelines to
wetlands it is important to keep the following points in mind:
• If Phytophthora dieback is present in a catchment area, wetlands located low in the
landscape within that catchment have a high likelihood of being infested.
• When preparing management guidelines which deal with restricting the movement
of water, it is important to consider the implications of restricting water movement
on the wetland water regime.
➤ For additional detail on wetland water regime see the topic ‘Wetland hydrology’
in Chapter 2.
(a) (b)
Figure 14. Phytophthora dieback hygiene management activities: (a) signage; and (b) bootcleaning station. Photos – Dieback Working Group.
h
Guidelines for the best practice management
of Phytophthora dieback
For landholders and community groups:
Dieback Working Group (2008). Managing Phytophthora dieback in
bushland: A guide for landholders and community conservation groups.2
For local government:
Dieback Working Group (2000). Managing Phytophthora dieback:
Guidelines for local government.20
For state government and other agencies:
Department of Conservation and Land Management (2003). Phytophthora
cinnamomi and disease caused by it: Volume I Management guidelines.3
Department of Conservation and Land Management (2004). Best practice
guidelines for the management of Phytophthora cinnamomi (Draft).11
Treating plants with phosphite
Phosphite, an aqueous solution containing phosphorus, has shown great promise in the
battle to preserve rare and endangered Western Australian native plants under threat
from P. cinnamomi. Depending on how it is applied, phosphite can provide protection
for vulnerable plant species against the disease for up to ten years. Phosphite is an
environmentally safe, inexpensive chemical that is systemically transmitted throughout
treated plants and has a very low toxicity to animals.
How it works
The mode of action of phosphite is not fully understood. At high enough concentrations,
phosphite will act directly on P. cinnamomi as a fungicide or fungistat to either kill or
halt its growth. This direct effect appears to occur within the P. cinnamomi organism,
but it also appears that the progress of infection by P. cinnamomi is halted when it
comes into contact with phosphite in plant tissue. This may be because high phosphite
concentrations interfere with the way that phosphorus is used by the pathogen
for survival. The application of phosphite may also trigger the plant’s self-defence
mechanism, causing it to wall-off and isolate the invaded root cells. Plants in poor health
which are treated in time have been shown to fully recover and remain healthy for a
number of years.
History of use
Previously called phosphonate, phosphite has been used to protect avocado, pineapple
and cocoa crops against Phytophthora disease since the 1970s. In the late 1980s
Department of Conservation and Land Management research staff began investigating
whether the fungicide provided any protection to Western Australian native plant
species. Phosphite solution was injected into jarrah (Eucalyptus marginata) and several
banksia species, and the treatments showed considerable promise; slowing and stopping
the growth of the pathogen within the plants under attack.21
Research efforts continued over the next decade and included field trials in locations
ranging from the northern sandplains near Eneabba to Fitzgerald River National Park east
of Albany. Aerial application of phosphite to native plant communities was tested for the
first time in 1993 in several reserves near Albany and proved a success. Aircraft allow for
relatively cheap and rapid treatment of entire plant communities containing rare plant
species, and are suitable for areas where the ruggedness of the terrain would make
ground application prohibitively expensive.
Fungicide: a substance that
kills fungi
Fungistat: a substance that
inhibits the growth and
reproduction of fungi without
destroying them
How it is applied
Phosphite is applied via stem injection (to trees with a diameter at chest height of 10–14
centimetres or greater22), or as a spray by aerial or ground application (Figure 15). One
drawback with aerially applied phosphite is that protection normally only lasts for about
two years, whereas stem injection may provide protection for up to ten years. There are
two main strategies for its application. Firstly, phosphite can be applied in an already
infested area to protect susceptible plants that have not yet been infected or help
already infected plants to recover.23 Secondly, phosphite can be used strategically for
effective protection ahead of an advancing ‘front’ of P. cinnamomi. A 30–40-metre-wide
swathe of phosphite can be applied in front of an advancing P. cinnamomi infestation to
prevent root-to-root transfer of the pathogen across the barrier.22 If the infested area is
upslope of the area to be protected the protective swathe would need to be wider than
if it is downslope. This is because of the possibility of overland or subsurface transport
of P. cinnamomi zoospores for considerable distances downslope following rainfall. In
contrast, movement of an infestation upslope is generally slower, being mainly caused by
root-to-root contact between plants.
Figure 15. (below) Application of phosphite via (a) spraying; and (b) stem injection.
Photos – Dieback Working Group.
(a)
(b)
h
Applying phosphite in wetlands
If applying phosphite, or any other chemical, in wetlands or other natural
environments it is important to minimise any off-target impacts such as
the unwanted decline or death of plants or animals. It is also important
to be aware that when phosphite is applied as a spray, by aerial or
ground application, it is mixed with a wetting agent to help droplets
hold onto leaf surfaces until they are absorbed. There are significant risks
associated with the use of wetting agents in wetlands and other aquatic
environments including toxic effects on tadpoles.24,25 As such, it is essential
that any off-target impacts of wetting agents are also minimised.
➤ For more information on reducing the off-target impacts of the application
of chemicals see the topic ‘Wetland weeds’ in Chapter 3.
The off-target impacts of chemicals (including wetting agents) can be
reduced and the effectiveness of application increased by:
•
selecting the correct application method (which will depend on
the type and size of plants being targeted, for example, using stem
injection where possible)
•
applying the chemical under ideal environmental conditions (for
example, dry, still wind conditions to minimise spray drift and timing
the application while susceptible fauna aren’t in a critical life phase
such a reproduction)
•
carefully following the manufacturer’s instructions.
The future
Research into phosphite and its application is continuing. Among the areas requiring
additional investigation is the refinement of application rates, times and frequencies for
different vegetation types. Phosphite cannot eradicate P. cinnamomi from an area once
it has established. However, by boosting the ability of plants to ward off infection, it
does provide some ability to protect endangered plants that might otherwise become
extinct in the wild within a few years. Nevertheless, the major strategy for limiting the
environmental damage caused by the pathogen remains the prevention of the transport
of infested soil into uninfested areas, by means of quarantine and the maintenance of
high standards of hygiene.
Monitoring the success of management and restoration
techniques
Monitoring is a key component of wetland management and restoration. The
information collected through monitoring can be used to assess if management is
successful, and if not, to adapt or modify the management (adaptive management).
In order to monitor the success of Phytophthora dieback management techniques it is
recommended that up-to-date Phytophthora dieback occurrence maps are prepared.
The frequency at which these maps need to be produced will be influenced by the
circumstances at a particular wetland. Specialist advice should be sought from an
interpreter or other specialist for more information. As Phytophthora dieback impacts
wetland vegetation, it is recommended that vegetation also be monitored to assess the
effectiveness of management activities.
➤ Additional detail on monitoring wetland vegetation is provided in the topic
‘Monitoring wetlands’ in Chapter 4.
Wetting agent: a substance
that helps water or other
liquid, to spread or penetrate
(also known as a surfactant or
penetrant)
case study
Chapter 3: Managing Wetlands
Manea Park – a collaborative approach to Phytophthora
dieback management
Manea Park is approximately 500 hectares in
size and is managed by the City of Bunbury for
conservation purposes. The reserve contains
more than 150 hectares of wetlands including
damplands, palusplains and sumplands. The
reserve also contains two threatened ecological
communities, which are both listed as vulnerable.
Both of these communities are wetlands (Figure
16).
Much of the flora of Manea Park is highly
susceptible to Phytophthora dieback and, as such,
an investigation into its distribution within the
park was conducted by the then Department of
Conservation and Land Management in 2001.
This survey found that up to half of Manea
Park was infested with the disease, including
many of the wetland areas and some heavily
degraded dryland areas. In 2007, the City of
Bunbury secured funding from Project Dieback
to have Manea Park reassessed and mapped
by a consultant. The results from the survey
undertaken by Glevan Consulting in 2008 strongly
mirrored the results of the 2001 assessment and
show that Phytophthora dieback has spread very
little since the original mapping exercise in 2001.
The survey undertaken in 2008 found that the
vegetation in around 36 per cent of the survey
area was sufficiently disturbed (by factors such as
clearing and grazing) that P. cinnamomi mapping
was not possible at the time of inspection, and
was otherwise referred to as ‘unmappable’. This
36 per cent included many of the wetlands within
the reserve. Of the area that was able to be
mapped, approximately 22 per cent was found
to be infested with P. cinnamomi.26 The survey
also found that it was predominately low-lying
wetlands in the north-west of the park that were
infested. Although many wetland plant species are
resistant to Phytophthora dieback, impacts of the
disease have been observed in a number of the
wetlands in Manea Park, including those recognised
as threatened ecological communities, with
deaths of swishbush (Viminaria juncea), swamp
banksia (Banksia littoralis) and swamp teatree
(Pericalymma ellipticum) recorded (Figure 17).
In mid-2008 the City of Bunbury decided to
take the next step in protecting Manea Park
from Phytophthora dieback by developing
management strategies for dieback-free areas or
‘protectable areas’ in the reserve. Limited areas
of wetland were included within the identified
protectable areas, as most of the wetland areas
within the reserve were identified as either being
infested with P. cinnamomi or unmappable.
Management strategies for protectable areas
were developed at a workshop with key
stakeholders including the Department of
Environment and Conservation, Department for
Planning and Infrastructure, Project Dieback, the
Friends of Manea Park and the City of Bunbury’s
consultant. It was agreed that track closure and
the control of track access were the most effective
strategies available. To complement these
strategies it was also agreed to erect interpretive
signage at strategic points throughout the
park to explain the current P. cinnamomi
infestation status and the management strategies
implemented to control its spread.
To manage those areas already infested by
P. cinnamomi, phosphite treatment will be
undertaken in a number of places, including
the wetland areas. This treatment will assist in
reducing the loss of plant species in these high
conservation value areas.
For further information contact the City of
Bunbury Environmental Officer.
Figure 16. One of the threatened ecological communities in
Manea Park near Bunbury. Photo – C Mykytiuk/DEC.
Figure 17. Deaths of swamp banksia (Banksia littoralis) in one
of the threatened ecological communities in Manea Park.
Photo – C Mykytiuk/DEC.
Whether or not to manage Phytophthora dieback in
a wetland
When deciding whether or not to manage Phytophthora dieback at a wetland, there
are a number of factors that should be considered, which will help focus the decisionmaking process. These include:
• What are the values under threat from Phytophthora dieback?
Example: Which plants species are susceptible to Phytophthora dieback? What will
be the impact of the loss of these species?
If the values under threat from Phytophthora dieback are significant, managing
dieback will be a higher priority.
• How practical and effective will management (hygiene management and
treatment with phosphite) be?
Example: Does Phytophthora dieback already occur throughout the site? Is the
wetland located low in the landscape within a catchment already infected with
Phytophthora dieback?
If management actions are unlikely to be effective in controlling and/or reducing the
impact of Phytophthora dieback at the site, it may not be a good use of resources to
implement these actions.
• Will management protect the values under threat?
Example: Are the values under threat from Phytophthora dieback, already
threatened by a potentially more significant degrading process such as altered
hydrology? Is the wetland already so significantly impacted by Phytophthora dieback
that management will not achieve improvements?
If managing Phytophthora dieback is not going to be sufficient to protect the values
under threat because they’re threatened by something else, or because the site is
already severely impacted by Phytophthora dieback, it may not be a good use of
resources to implement these actions and instead resources may be better directed
towards managing another degrading process.
• How urgent is the need for action – at what rate is Phytophthora dieback
diminishing wetland values?
Example: Is Phytophthora dieback causing a rapid and significant loss of plants? Is the loss
of plants from Phytophthora dieback relatively slow over time?
Threats that are having a rapid impact would generally be a higher priority for
management than threats that act very slowly.
• What are the financial and other costs (such as time and labour) of carrying
out management activities?
Example: How do financial and other costs of Phytophthora dieback mapping
and hygiene management weigh up against the values under threat? How do the
financial and other costs of phosphite treatment weigh up against the values under
threat?
Management will be most cost effective and beneficial if the site has high values, and
the cost of management actions is relatively low.
• Taking into account the management of other threats or degrading processes
– what is the most logical sequence for undertaking management actions?
Example: If it is planned to close tracks or paths as part of a hygiene management
plan, it should be determined whether the paths are needed for other management
activities, such as providing access to remove car bodies or other rubbish?
All threats and degrading processes need to be documented for the site, and any
possible links between these identified prior to planning on-ground management.
In some situations, it may be necessary to make decisions regarding the management of
Phytophthora dieback across multiple wetlands within one landscape or management
area. In these situations, the questions listed above will still be a useful guide to
decision-making. Often it is most effective to focus resources on those wetlands that
are minimally degraded and still have high values, as intervention is likely to be most
successful, and have most conservation value at these sites.21
In an ideal situation, any management activities should be undertaken as part of a
comprehensive wetland management plan which would address other management
issues or degrading processes and their associated management activities. It is strongly
encouraged that a management plan is prepared, however basic it may be.
➤ For additional detail on preparing a wetland management plan see the topic ‘Planning
for wetland management’ in Chapter 1.
Topic summary
• Phytophthora dieback refers to the introduced plant disease caused by the
microscopic soil-borne organism Phytophthora cinnamomi.
• P. cinnamomi invades the roots of plants, killing cells, reducing the ability of a plant to
take up and transport water and nutrients, often resulting in the death of the plant.
• Many common wetland species are susceptible to Phytophthora dieback, however
field observations have suggested that a large number of wetland species are
resistant to P. cinnamomi, hence wetland plant communities often don’t exhibit signs
of Phytophthora dieback disease.
• The loss of native vegetation as a result of Phytophthora dieback can have a number
of detrimental impacts on wetlands including increasing the risk of erosion and
sedimentation, reducing water quality, loss of biodiversity, loss of habitat and food for
native fauna and a subsequent decline in native fauna.
• The fact that most wetlands are located low in the landscape means that they have
a highly likelihood of being infested if Phytophthora dieback is located within their
catchments.
• Once present, P. cinnamomi cannot be eradicated from an area. As such, the
management of Phytophthora dieback is focused on minimising the spread of the
pathogen to disease-free areas.
• The management of Phytophthora dieback is based on minimising the movement of
soil, plant material and water, and protecting plants by treating them with phosphite.
• The management of Phytophthora dieback in wetlands can be summarised into three
steps:
1. assess the site and map Phytophthora dieback occurrence
2. prepare and implement management guidelines
3. treat plants with phosphite.
• When deciding whether or not to manage Phytophthora dieback at a wetland, there
are a number of factors that should be considered including the values under threat,
how practical and effective will management be, and the financial and other costs
(such as time and labour) of carrying out management activities.
Sources of more information on managing
Phytophthora dieback in wetlands
Websites
Dieback.org.au
www.dieback.org.au
Information on the impacts of Phytophthora dieback and its management. Designed to be
a one-stop shop for information on how to manage Phytophthora dieback.
Dieback Working Group
www.dwg.org.au
Information on the impacts of Phytophthora dieback and its management.
Project Dieback
www.dieback.net.au
Information on the impacts of Phytophthora dieback, maps of its distribution within the
south-west, and lists of susceptible and resistant species in the South Coast NRM region.
Centre for Phytophthora Science and Management
www.cpsm.murdoch.edu.au
Information on Phytophthora dieback research, links to national best practice guidelines,
and list of susceptible and resistant species.
Department of Environment and Conservation
www.dec.wa.gov.au (search for ‘Phytophthora’)
Information on the impacts of Phytophthora dieback and its management, state
government Phytophthora dieback policy, Phytophthora dieback Atlas.
Department of Sustainability, Environment, Water, Population and Communities
www.environment.gov.au (search for ‘Phytophthora’)
Information on Phytophthora dieback management and threat abatement.
Publications
Department of Conservation and Land Management (1998). Management of
Phytophthora dieback and diseases caused by it: Policy statement No.3.27
Department of Conservation and Land Management (1999a). Trunk injection of the
fungicide Phosphite for protection against Phytophthora disease.28
Department of Conservation and Land Management (1999b). Phytophthora cinnamomi
and disease caused by it: Volume III Phosphite operations guidelines (Draft).22
Department of Conservation and Land Management (2001). Phytophthora cinnamomi
and disease caused by it: A protocol for identifying ‘protectable areas’ and their priority for
management.29
Department of Conservation and Land Management (2003). Phytophthora cinnamomi and
disease caused by it: Volume 1 Management guidelines.3
Department of Conservation and Land Management (2004). Best practice guidelines for
the management of Phytophthora cinnamomi (Draft).11
Department of Environment and Conservation (2009). Phytophthora dieback: Detecting
the pathogen.30
Dieback Working Group (2000). Managing Phytophthora dieback: Guidelines for local
government.20
Dieback Working Group (2008). Managing Phytophthora dieback in bushland: A guide for
landholders and community conservation groups.2
W O’Gara, K Howard, B Wilson and GESTJ Hardy (2005). Management of Phytophthora
cinnamomi for biodiversity conservation in Australia: Part 2 National best practice guidelines.6
Glossary
Agar: a gelatinous substance obtained from any of various kinds of red seaweed and
used to grow cultures of fungi and other microorganisms
Dieback: the progressive dying back of a plant as a result of disease or unfavourable
conditions
Epicormic: (of a shoot or branch) growing from a previously dormant bud on the trunk
or limb of a tree
Fungicide: a substance that kills fungi
Fungistat: a substance that inhibits the growth and reproduction of fungi without
destroying them
Germinate: begin to grow, usually following a period of dormancy (resting phase)
Geophytes: land plants that survive unfavourable periods by means of underground
food-storage organs, for example rhizomes, tubers and bulbs
GPS: global positioning system, an accurate worldwide navigational and surveying facility
based on the reception of signals from an array of orbiting satellites
Mycelium: the vegetative part of a fungus, consisting of microscopic thread-like
filaments known as hyphae
Oomycetes: the group of fungae-like organisms known as the water moulds
Pathogen: any organism or factor causing disease within a host
Phytophthora cinnamomi: an introduced water mould that attacks the roots of
susceptible plant species, resulting in the decline or death of the plant
Phytophthora dieback: the introduced plant disease caused by Phytophthora
cinnamomi, which results in the decline or death of susceptible plants
Petri dish: a shallow covered dish used for the culture of fungi and other
microorganisms
Phosphite: an aqueous solution of mono- and di-potassium phosphite used to protect
plants against Phytophthora dieback
Wetting agent: a substance that helps water or other liquid, to spread or penetrate
(also known as a surfactant or penetrant)
Personal communications
Name
Date
Position
Organisation
Chris Dunne
26/09/2008
Senior Research
Scientist
Department of Environment
and Conservation, Western
Australia
Dr Bryan Shearer
21/01/2009
Principal Research
Scientist
Department of Environment
and Conservation, Western
Australia
References
1.
Dieback Working Group (2005). Install firebreaks not Phytophthora. Dieback Working
Group, Western Australia. www.dwg.org.au/index.cfm?objectid=0BDB924E-65BFEBC1-2E1D363384E7B4F1&navid=64E36F56-C09F-1F3C-C8184462BD3A1522.
2.
Dieback Working Group (2008). Managing Phytophthora dieback in bushland: A guide
for landholders and community conservation groups. Dieback Working Group and
Threatened Species Network, Western Australia.
www.dwg.org.au/go/publications-and-downloads/publications/index.cfm.
3.
Department of Conservation and Land Management (2003). Phytophthora cinnamomi
and disease caused by it: Volume I Management guidelines. Department of
Conservation and Land Management, Perth, Western Australia.
www.dec.wa.gov.au/land/dieback/more-information.html.
4.
Department of Environment and Conservation (2009). Managing dieback: Lifecycle
of Phytophthora cinnamomi. Department of Environment and Conservation, Perth,
Western Australia. www.dec.wa.gov.au/land/dieback/managing-dieback/lifecycle.html.
5.
Dieback Working Group (2009). Phytophthora life cycle. Dieback Working Group,
Western Australia. www.dwg.org.au/images/dwg-lifecycle.jpg.
6.
O’Gara, W, Howard, K, Wilson, B, and Hardy, G (2005). Management of Phytophthora
cinnamomi for biodiversity conservation in Australia: Part 2 National best practice
guidelines. A report funded by the Commonwealth Government Department of the
Environment and Heritage by the Centre for Phytophthora Science and Management,
Murdoch University, Western Australia.
www.environment.gov.au/biodiversity/invasive/publications/p-cinnamomi.html.
7.
Shearer, BL, Crane, CE, and Cochrane, A (2004). ‘Quantification of the susceptibility
of the native flora of the south-west botanical province, Western Australia, to
Phytophthora cinnamomi’, Australian Journal of Botany, vol. 52, pp. 435–443.
8.
Erwin, DC and Riberio, OK (1996). Phytophthora diseases worldwide. APS Press, St.
Paul, Minnesota, USA.
9.
Cahill, D (1993). Review of Phytophthora diseases in Australia. Rural Industries
Resource and Development Corporation. Report Series No. 93/94. Department of
Primary Industries and Energy, Canberra, Australia Capital Territory.
10. Department of Conservation and Land Management (2005). Interim recovery plan
no. 215: Shrubland association on southern Swan Coastal Plain ironstone (Busselton
area) (southern ironstone association). Interim recovery plan 2005–2010. Prepared by
R Meissner and V English, Department of Conservation and Land Management, Perth,
Western Australia.
11. Department of Conservation and Land Management (2004). Best practice guidelines
for the management of Phytophthora cinnamomi (Draft). Department of Conservation
and Land Management, Perth, Western Australia.
www.dec.wa.gov.au/component/option,com_docman/Itemid,/gid,316/task,doc_
details/.
12. Wilson, BA, Newell, G, Laidlaw, WS, and Friend, GR (1994). ‘Impact of plant diseases
on faunal communities. In: Plant diseases in ecosystems - Threats and impacts in
south-western Australia’, Journal of the Royal Society of Western Australia, vol. 77, pp.
139–143.
13. Department of Environment and Conservation (2009). Managing dieback: Impacts in
WA. Department of Environment and Conservation, Perth, Western Australia.
www.dec.wa.gov.au/land/dieback/managing-dieback/impacts-in-wa.html.
14. Hill, TCJ, Tippett, JT, and Shearer, BL (1994). ‘Invasion of Bassendean dune banksia
woodland by Phytophthora cinnamomi’, Australian Journal of Botany, vol. 42, pp.
725–738.
15. Duniway, JM (1976). ‘Movement of zoospores of Phytophthora cryptogea in soils of
various textures and matric potentials’, Phytopathology, vol. 66, pp. 877–882.
16. Kinal, J, Shearer, BL, and Fairman, RG (1993). ‘Dispersal of Phytophthora cinnamomi
through lateritic soil by laterally flowing subsurface water’, The American
Phytopathological Society, vol. 77, pp. 1085–1090.
17. Mosely, MP (1982). ‘Subsurface flow velocities through selected forest soils, South
Island, New Zealand’, Journal of Hydrology, vol. 55, pp. 65–92.
18. Centre for Phytophthora Science & Management (2009). Western Australian native
plants susceptible and resistant to Phytophthora cinnamomi. Centre for Phytophthora
Science & Management, Western Australia.
www.cpsm.murdoch.edu.au/html/links_PCresist.html.
19. Centre for Phytophthora Science & Management (2009). Symptoms and signs of
Phytophthora cinnamomi. Centre for Phytophthora Science & Management, Western
Australia. www.cpsm.murdoch.edu.au/html/signs_symptoms.html.
20. Dieback Working Group (2000). Managing Phytophthora dieback: Guidelines for local
government. Dieback Working Group, Western Australia.
www.dwg.org.au/go/publications-and-downloads/publications/index.cfm.
21. Department of Environment and Conservation (2009). Managing dieback: Using
phosphite. Department of Environment and Conservation, Perth, Western Australia.
www.dec.wa.gov.au/land/dieback/using-phosphite.html.
22. Department of Conservation and Land Management (1999). Phytophthora cinnamomi
and disease caused by it: Volume III Phosphite operations guidelines (Draft).
Department of Conservation and Land Management, Perth, Western Australia.
23. Dieback Working Group (2009). Phosphite treatment: Treating your plants with
phosphite. Dieback Working Group, Western Australia.
www.dwg.org.au/go/about-dieback/phosphite-treatment/index.cfm.
24. Mann, RM (2000). Toxicological impact of agricultural surfactants on Australia frogs.
PhD thesis. Curtin University of Technology, Western Australia.
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selected frog species. Prepared by J R Bidwell and J R Gorrie, Curtin University of
Technology for the Department of Environmental Protection, Perth, Western Australia.
26. Glevan Consulting (2008). Phytophthora cinnamomi occurrence mapping: Ocean to
Preston River Regional Park (in part) and Loughton Park Reserve
(in part). Project Dieback and the City of Bunbry, Western Australia.
27. Department of Conservation and Land Management (1998). Management of
Phytophthora dieback and diseases caused by it: Policy statement No.3. Department of
www.dec.wa.gov.au/land/dieback/manuals-documents-and-information-sheets.html.
28. Department of Conservation and Land Management (1999). Trunk injection of the
fungicide Phosphite for protection against Phytophthora disease. Department of
29. Department of Conservation and Land Management (2001). Phytophthora cinnamomi
and disease caused by it: A protocol for identifying ‘protectable areas’ and their priority
for management. Department of Conservation and Land Management, Perth, Western
Australia.
2009185-1011-PDF
30. Department of Environment and Conservation (2009). Information sheet 8/2009.
Science Division: Phytophthora dieback: Detecting the pathogen. Prepared by M
Stukely, Science Division, Department of Environment and Conservation, Perth,
Western Australia.

Phytophthora dieback1.02 MB - Department of Parks and Wildlife

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